Serum cystatin C(Cys C) and creatinine(Cr) concentrations were detected in 283 inpatients with CKD and 9 307 outpatients, and the eGFR of 3 CKD-EPI equations (Cr-, Cys C- and Cys C-C equations), 2 Chinese eGFR investigation collaboration equations (Cys C- and Cys C-C equations) and 2 FQ-eGFR equations (Cys C- and Cys C-C equations) were calculated as the order of eGFR1-eGFR7. Plasma ^99mtechnetium-diethylene triamine pentacetic acid (^99mTC-DTPA) clearance rate as measured glomerular filtration rate (mGFR) was detected in 283 inpatients with CKD, and was used as a gold standard for evaluating difference, consistency and performance of eGFR. The incidence rate ratio (IRR) of each eGFR predicting CKD was analyzed retrospectively in 9 307 outpatients.

There were significant differences between eGFR2 and eGFR3 with mGFR (P=0.000). The concordance correlation coefficients (ρ_c)of eGFR4, eGFR6 and eGFR7 with mGFR were all significantly higher than that of eGFR1 (P<0.01). For the patients with mGFR<60mL/(min·1.73 m²), the deviation, precision and accuracy of eGFR4, eGFR6 and eGFR7 had quite correspondence(P>0.05), and had significant differences with those of eGFR1(P<0.05). In contrast, the deviation of eGFR4 was smaller [median (M)=0.3 mL/(min·1.73 m²)], the precision of eGFR6 was higher [standard interquartile range (IQR)=7.7 mL/(min·1.73 m²)], and the accuracy of eGFR7 was better (1-P₃₀=13.8%). The incidence rates of predicting CKD by eGFR4, eGFR6 and eGFR7 were higher than that by eGFR1 (P<0.01), and were greatly higher in elderly (>65 years old) compared with in under 65 years old (P=0.000).

CKD-EPI equations could not provide an accurate assessment of kidney function for Chinese adult patients with CKD, whose GFR<60 mL/(min·1.73 m²). In contrast, it would be more appropriate for the screening of diseases and early diagnosing used Cys C- equation, FQ-eGFR Cys C- equation or FQ-eGFR Cys C-C equation of Chinese eGFR investigation collaboration equations, in which it is as far as possible to prevent leak-diagnosis or misdiagnosis when FQ-eGFR Cys C- equation is used for the screening of diseases.